Controlled potential electrolysis gas sensor

The present invention has as its object the provision of a controlled potential electrolysis gas sensor capable of speedily obtaining a state in which gas concentration measurement can be conducted after the activation of a power source.The controlled potential electrolysis gas sensor is configured to include at least a working electrode and a counter electrode which are provided in contact with an electrolytic solution and to detect a concentration of a detection target gas in a gas to be tested by detecting a current flowing between the working electrode and the counter electrode in a state in which the working electrode is controlled at a constant set potential. The controlled potential electrolysis gas sensor includes an operation control circuit that drives the controlled potential electrolysis gas sensor based on a current in a forward direction detected when the controlled potential electrolysis gas sensor is activated under energization conditions at the time of a gas detection operation.